"In Windows 8, we reimagined the browser with IE10. We designed and built IE10 to be the best way to experience the Web on Windows. With the IE10 Release Preview for Windows 7 consumers can now enjoy a fast and fluid Web with the updated IE10 engine on their Windows 7 devices. The release preview of IE10 on Windows 7 is available for download today."

My hope is that Opus will find broad adoption eventually. It is not just an open codec with a great free implementation (in floating- and fixed-point variants), it is also part of the official IETF WebRTC standard. Microsoft was part of the development team (via Skype) and Opus showed to be better than Vorbis, MP3 and AAC in listening tests most of the time. It is said to be the best low bitrate and the best high bitrate lossy codec all in one (well, it does consist of two sub-codecs).

I hope opus support will come as an update to IE 10 (and thus also to Windows 7). But if not I think it should at least be supported by IE 11.